1. Field of the Invention
This invention relates to the synthesis and production of Lewis base adducts of anhydrous mononuclear tris(.beta.-diketonate) bismuth compositions e.g., anhydrous mononuclear tris-(2,2,6,6-tetramethyl-3,5-heptanedionato) bismuth N,N,N'N'-tetramethylethylenediamine adduct. Such bismuth-containing compositions have utility as precursors for chemical vapor deposition of bismuth, bismuth oxide, bismuth-containing oxides and bismuth-containing chalcogonides.
2. Description of the Related Art
Ferroelectric random access memories (FRAMs) rely on high-integrity ferroelectric thin-films as critical components of memory cell architecture.
Electrical performance of ferroelectric oxides such as SrBi.sub.2 Ta.sub.2 O.sub.9 (SBT) show a strong dependence on the identity of the precursor used in depositing the Bi component in the ferroelectric material. For example, the use of a Bi precursor such as triphenyl bismuth results in poor stoichiometric control, high substrate temperatures to decompose the precursor, strong surface dependence, and extreme dependence of the precursor incorporation efficiency on reactor pressure and partial pressure of oxygen during deposition.
To ameliorate the foregoing deficiencies, the art has continued to seek other bismuth precursors.
One such bismuth-containing precursor candidate is tris(2,2,6,6-tetramethyl-3,5-heptanedionato) bismuth tetramethylethylenediamine adduct. As used hereinafter, the ligand "2,2,6,6-tetramethyl-3,5-heptanedionato" is sometimes referred to by the designation "thd" and the tetramethylethylenediamine adduct is sometimes referred to by the designation "tmeda."
It is an object of the present invention to provide an improved class of bismuth precursors for deposition of Bi for applications such as ferroelectric thin film devices, chalcogonides and thermoelectric films.
Other objects and advantages of the present invention will be more fully apparent from the ensuing disclosure and appended claims.